Unit for heating and dispensing aerosol products

ABSTRACT

A DISPENSER UNIT FOR HEATING AND DISPENSING AN AEROSOL PRODUCT, COMPRISING AN EXTERIOR SHELL MEMBER HAVING AN OPENING IN ONE END FOR RECEIVING AN AEROSOL CONTAINER, AND A COMBINATION PRODUCT HEATER AND DISPENSER INCLUDING AN IMPROVED NOZZLE, AT THE OTHER END OF THE SHELL. THE HEATER AND DISPENSER INCLUDES A RELATIVELY MASSIVE HEAT EXCHANGER HAVING A PRODUCT INLET, A PRODUCT OUTLET, AND A CIRCUITOUS PASSAGE CONNECTING THE TWO, AND IS HEATED BY HEATING ELEMENT MEANS OF VARIABLE RESISTANCE. THE HEAT TRANSFER BETWEEN THE VARIABLE RESISTANCE HEATING MEANS AND THE EXCHANGER IS FACILITATED BY SURROUNDING THE HEATING ELEMENT WITH AN ELECTRICALLY INSULATING, HEAT CONDUCTIVE MATERIAL, PREFERABLY A FILED SILICONE GREASE, WHICH IS IN INTIMATE HEAT EXCHANGER CONTACT WITH THE EXCHANGER. THE PRODUCT DISPENSED FROM THE CONTAINER IS A FLOWABLE, FOAMABLE PRODUCT, WHICH INCLUDES A GASEOUS FOAMING AGENT THEREIN. THE CONTAINER IS PREFERABLY A TWO-COMPARTMENT CONTAINER COMPRISING AN OUTER PORTION WHICH INCLUDES A PROPELLANT HAVING A LIQUID-VAPOR EQUILIBRIUM AT AMBIENT TEMPERATURES, AND A FLEXIBLE, INNER PORTION FOR THE FORMABLE PRODUCT, SO THE PRODUCT MAY BE DISPENSED AT A CONSTANT OVERPRESSURE AND   WITH A CONSTANT CONCENTRATION OF VOLATILE FOAMING AGENT THEREIN.

United States Patent [72] Inventor WarrenLGtosjean Trumbull,Conn. [21]AppLNo. 754,177 [22] Filed Aug.2l,1968 [45] Patented June28, 1971 [73]Assignee EversharpJnc.

Milford, Conn.

[54] UNIT FOR HEATING AND DISPENSING AEROSOL PRODUCTS 6 Claims, 15Drawing Figs.

[52] U.S.Cl 219/214, 219/30l,219/302,219/327,222/146,239/135 [51] lnt.Cl867d 5/62, 1105b 3/00 [50] FieldofSear-ch 219/296- -309, 327, 328;222/146, 146(1-1A), 146 (HE); 239/135 [5 6] References Cited UNITEDSTATES PATENTS 941,215 11/1909 Wade; 219/303 1,778,915 10/1930Richardson 219/301 2,037,993 4/1936 Milleretal. 219/308 2,104,045 1/1938Knopp 219/301x 2,472,713 6/1949 Lijoi"... 219/304 3,116,403 12/1963Carter 2l9/301X 3,187,226 6/1965 Kates 317/100 3,307,747 3/1967 Pacitti219/306X 3,338,476 8/1967 Marcoux 222/146 3,358,885 12/1967 Flowers222/146 3,476,293 11/1969 Marcoux 222/146 Primary Examiner-A. BartisAttorney-Greist, Lockwood, Greenawalt & Dewey ABSTRACT: A dispenser unitfor heating and dispensing an aerosol product, comprising an exteriorshell member having an opening in one end for receiving an aerosolcontainer, and

a combination product heater and dispenser including an im- I provednozzle, at the other end of the shell. The heater and dispenser includesa relatively massive heat exchanger having a product inlet, a productoutlet, and a circuitous passage connecting the two, and is heated byheating element means of variable resistance. The heat transfer betweenthe variable resistance heating means and the exchanger is facilitatedby surrounding the heating element with an electrically insulating, heatconductive material, preferably a filled silicone grease, which is inintimate heat exchange contact with the exchanger. The product dispensedfrom the container is a flowable, foamable product, which includes agaseous foaming agent therein.

The container is preferably a two-compartment container comprising anouter portion which includes a propellant having a liquid-vaporequilibrium at ambient temperatures, and a flexible, inner portion forthe foamable product, so the product may be dispensed at a constantoverpressure and with a constant concentration of volatile foaming agenttherein.

PATENTEU JUH28 l9?! SHEET 1 HF INVENTOR WARREN J. GROSJEANPATENTEDJUN28I97I 3588467 SHEET 2 0F 5 INVENTOI'? j WARRENJGROSJEAN BYATT'YS.

PATENTED M2819?! SHEET 3 BF 5 INVENTOR WA RREN J. GROSJEA NPATENTElJJunzalsn 34,588,467

' saw u UF 5 I82 I68 56 I I 52 HEAGTRECZAOQEDUCTIVE GREASE INVENTORWARREN J. GROSJEAN ATT'YS.

PATENTED JUN28 I97! SHEET 5 OF 5 K \W I [1]] LII I'" INVENTOR WARREN J.GROSJEAN ATT' YS.

UNIT FOR HEATING AND DISPENSING AEROSOL PRODUCTS BACKGROUND OF THEINVENTION 1. Field of the Invention 1 The field of the present inventionis that of combination heater and dispenser units. In particular, thefield is that of units adapted to be used with aerosol containers, inwhich the heating means includes a control means, and in which thedisposition of the parts and selection of materials is such that highefficiency may be maintained, while a variable temperature controlarrangement may be incorporated at very low cost. In another aspect, thefield of the invention is that of improved heat exchange devices andheater elements therefor, particularly wherein the heat which would begenerated in a rheostat-heating element, is rapidly supplied to arelatively massive heat exchanger unit, thereby making efficient use ofthe rheostat as a heating element and allowing a greater quantity ofheat to be transferred through a unit of lower power rating than wouldotherwise be possible.

In another aspect, the invention relates to means associated with thedispenser, in the form of a novel nozzle or spout unit, which preventsundesired discharge of an expansible foam product from the nozzle, afterclosing the actuating means supplying the foamable product from anaerosol container.

in still another aspect, the field of the invention is that of improvedaerosol products, and containers including such products, wherein theproduct and its foaming agent are contained in a flexible innercompartment of a container, and in which the propellent component iscontained in another, rigid compartment of the container. As thepropellant undergoes vaporization from a liquid stage at a givenequilibrium temperature, the product in the interior compartment isdispensed with a relatively constant overpressure thereon. One aspect ofthe invention is therefore that of aerosol compositions which aredesigned to maintain a relatively constant percentage of a volatilecomponent even after dispensing significant amounts thereof.

2. Description of the Prior Art in general, aerosol heating anddispensing devices of the prior art have fallen into the category ofthose in which the product to be dispensed, generally in the form of afoamable composition, was heated by means of a heat exchanger which waswarmed by being contacted with hot water. In the case of such aerosoldispensers, the heat was absorbed from the water and held in a heatexchanger until the dispensing operation was performed. Units such asthese are satisfactory in some cases, but they are only usefulimmediately after the heat exchanger has been exposed to the hot water,and are obviously useful only where significant amounts of sufficientlyhot water are readily available. In addition, such dispenser units mustbe used immediately after the heat exchanger has been warmed, ratherthan sometime thereafter, and accordingly, such units are limited to useunder such conditions.

Another form of heat exchanger device contains an electrically heatedheat exchanger. In such units, the advantages of electric heating arepresent, and although such units have been commercially successful to acertain extent, they are capable of improvement. In general, such unitsof the prior art are adapted to be plugged in or switched on shortly orimmediately before use, and a certain warmup period is generallyrequired before the heat exchanger reaches the desired temperature.Units capable of fast warmup generally include a heating element ofrelatively high capacity and relatively large size, and if it is desiredto use them frequently, such as in barber shops, they must be switchedon and off a number of times. If they are used infrequently, a givenwarmup time must be allowed before they are usable. Accordingly, suchunits are not advantageously used where a heated product is desirablyavailable at all times, or where the units are to be turned on and offfrequently.

Thus, the prior art has not provided an electrically heated dispenserunit which may be economically used in continuous operation, that is,one which may be energized and left in an on" position for a relativelylong time so that the same may be always ready for use, and yet notconsume significant amounts of current between uses thereof.Particularly, the art has not taught the use of very efficient, butreliable and inexpensive heating elements, heat exchangers, and meansfor l0- calizing the heat generated in a desired area, where it may beretained for a reasonable time.

Prior art shaving compositions, and pressurized cans containing suchcompositions, have also presented a further problem to the prior art.For example, in the case of an ordinary shaving compositions dispensedthrough an electrically heated heat exchanger, the user of the heatedlather was able to detect that there was a considerable variation in thetemperature of the lather emanating from a full container and thetemperature of the lather coming from a nearly empty can. This is aresult of the change of proportions of the constituents of the productduring dispensing, that is, there is a reduction in the percentage ofthe combination volatile propellant and foaming agent therein when theproduct supply in the container can is nearly exhausted as compared towhen it is nearly full. With a heat exchanger of given heat capacity,the result is a lather or cream varying in dispensing temperature, sinceexposure of the same amount of lather to the same amount of heat for thesame time creates a lower temperature in a foam having greater heatcapacity. Such compositions and containers, accordingly, when used withcombination dispenser and heating units, possessed this characteristicdrawback.

Another shortcoming in combination dispenser and heating units of theprior art is that foam contained in the heat exchanger tends to continueto foam out of the discharge nozzle even after the supply of product isshut off, that is, dispensers with large nozzles tend to drool" afteruse.

SUMMARY OF THE INVENTION Accordingly, in view of the shortcomingspossessed by certain prior art devices, and the apparent failure ofattempts to solve the problems inherent with an aerosol product heaterand dispenser, there has been a need for an economical and reliablecombination dispenser and product heater having a relatively large heatcapacity, being in simple construction, and having other novel featuresand advantages.

Another object of the invention is to provide a combination dispenserand heating unit in which the heat exchanger is a relatively massivemetal element in intimate heat exchange contact with a variableresistance heater unit, and which includes an additional heat transferand electrical insulation means surrounding the heating element toincrease the effectiveness thereof in use of the unit.

A further object of the invention is to provide a heater and dispenserunit in which the heating element is a rheostat unit, and in which thecurrent fed to the rheostat is furnished through a stepdown transformer.

The further object of the invention is to provide a combination heatingand dispenser unit including a rheostat and a transformer, wherein theresistance of the rheostat may be adjusted so as to match the impedanceof the transformer secondary, or to differ widely therefrom.

Another object of the invention is to provide an aerosol composition andcontainer therefor, in which the product and foaming agent are containedin an inner, collapsible portion of the container, and the propellant inan outer, rigid portion, and in which the propellant is present in boththe gas or liquid and gas phase, thereby serving to exert a relativelyconstant dispensing pressure and counterpressure on the composition.

Another object is to provide a dispenser for use with foamable aerosolproducts in which means are provided for preventing excessive expansionand discharge of the foamed product from the heat exchanger after theproduct supply to the heat exchanger has been cutoff.

A further object is to provide a dispenser having the above advantagesand characteristics, which is capable of being manufactured economicallyand which affords a high degree of reliability and safety in use.

Another object is to provide an aerosol heater and dispenser which iscapable of providing excellent results with specially prepared foamablecompositions and containers, but which will also provide excellentresults with ordinary foamable aerosol compositions.

The present invention achieves these objects, and others which areinherent therein, by providing a dispenser unit for heating anddispensing an aerosol product, which includes an exterior shell with anopening at one end thereof, and a heater and dispenser'unit at the otherend which comprises a relatively massive heat exchanger having an inlet,an outlet, and a circuitous passage connecting the two, and variableresistance heating element means for heating the heat exchanger.Additionally, the invention achieves other objects by providing acomposition and container combination wherein a propellant is containedin the outer portion of a container, the foamablc composition, includingthe foaming agent, is contained in an inner, flexible compartment of thesame container, and in which the propellant and the foamable compositioneach include components which are present both in the liquid and in thegas phase. Further, the invention achieves its objects by providing animproved nozzle construction in the dispenser unit for eliminatingundesirable after dispensing or drool. Preferably, the dispenserincludes additional means for facilitating heat transfer between theheating element means and the heat exchanger.

The exact manner in which the invention accomplishes these, and otherinherent objects and advantages, will become more apparent when thedescription proceeds, and particularly when the description of theinvention is considered in conjunction with the accompanyingdrawings, inwhich like reference numerals indicate corresponding parts throughout.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is an exploded perspective viewof the combination heating and dispensing unit of the invention, showingthe principal elements thereof;

FIG. 2 is a vertical sectional view, taken through the heating anddispensing unit of the invention, which is shown in association with acontainer of the product to be dispensed;

FIG. 3 is a top plan view of the heater and dispenser unit of theinvention; 1

FIG. 4 is an exploded view of one form of heat exchanger of theinvention;

FIG. 5 is a top plan view of the upper portion of the heat exchanger ofFIG. 4;

FIG. 6 is a bottom plan view of the upper portion of the heat exchanger;

FIG. 7 is a bottom plan view of the lower portion of the heat exchanger;

FIG. 8 is a top plan view of the lower portion of the heat exchanger;

FIG. 9 is an electrical schematic diagram of the transformer and heatingelement means of the invention;

FIG. 10 is an enlarged vertical sectional view, with portions brokenaway, of the heating element means and a part of the heat exchanger ofthe invention;

FIG. 11 is a horizontal sectional view of the heating element means ofFIG. 10, taken along lines 11-11 thereof;

FIG. 12 is an exploded perspective view of a modified form of the heatelement means and heat exchanger of the invention;

FIG. 13 is an enlarged vertical sectional view, with portions brokenaway, showing the modified form of the heating element and heatexchanger of FIG. 12;

FIG. 14 is a further enlarged vertical sectional view of the heatingelement'means and heat exchanger of FIGS. 12 and 13;

FIG. 15 is a vertical sectional view of a container unit and producttherein which is preferred for use with the dispenser of the invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS OF THE INVENTION Referring nowto the drawings in greater detail, the combination heating anddispensing unit is shown at 20 in FIG. 1. The principal components ofthe illustrated unit comprise the shell 22 which includes leftandright-hand halves 24,26, each including vent means 28 on the sidesthereof, cord housing means 30 at the rear thereof, nozzle formingportions 32,34, and means in the form of a supporting flange 36 near thebottom of the shell 22 for supporting an aerosol container, and a ramp38, which forms, in combination with other portions of the flange 36,means for removably receiving an aerosol container or parts associatedtherewith, and for allowing free but limited movement of such containervertically within the shell.

Another principal element of the dispenser is the heat exchanger unit40, which will be described in further detail herein, but which is hereshown to include outlet means 42 for a product, and projections 44extending upwardly from the upper portion 46 of the heat exchanger 40. Alower portion 48 is secured by fasteners 50 or the like to the upperportion 46 of the heat exchanger 40.

Another principal component of the invention is the heating elementmeans 52, which is-shown in the form of a rheostat having an exteriorcover 54, electric lead means in the form of terminals 56 and controlmeans in the form of a stem 58 which is rotatably received in the topcover portion 60 of the heating element 52. The other features of thisunit will be described in further detail herein.

FIG. 1 also shows a top cover means in the form of a cover element 62which includes a central opening 64 in the top thereof to allowprojection of the shaft 58 therethrough, and means in the form of a ring66 for receiving a dial unit 68 disposed on top of the cover 62. Theremaining principal elements of the invention comprise an aerosolcontainer 70 and a base unit 72, the container having an outlet in theform of a vertically extending, cylindrical valve 74 supported in amounting cup 76. The base 72 receives the bottom double seam 78 of thecontainer 70, and includes a bottom wall 80, sidewalls 82, means in theform of a groove 84 for receiving the double seam 78, and a plurality oflocking and Supporting lugs 86 disposed about the upper peripherythereof. The lugs 86 are adapted, upon rotation of the can within theshell, to ride upwardly on the ramp 38 and, after positioning thecontainer within the shell 32, to remain in position on top of theflange 36, thus supporting the can or container 70 in position of usewithin the shell 22. i

Referring now to FIG. 2, certain construction features of the unit arebetter shown. This view shows that the shell 22, upon assembly, forms aunitary cover, and that the container 70 is movable within the shell 22as shown in the phantom lines. Extreme downward movement is limited bythe engagement of the lugs 86 with the flange 36, and upward movement islimited by the travel limit of the aerosol valve 74 or the en gagementof the upper portions of the mounting cup 76 'with the lower portion 48of the heat exchanger. A cord unit 88 is supplied for connection to atransformer assembly 90 which will be described in further detailherein. The housing 30 supports the cord 88 in place within the shell22. 7

Referring now to the construction of the heat exchanger, it will be seenthat the unit is of massive, substantially solid metal construction andthat it includes a downwardly extending, reduced diameter boss 92 havinga re-entrant portion 94, terminating in inwardly facing, verticalcylindrical walls 96, surmounted by a shoulder 98, the walls andshoulder 98 serving to define a cylindrical opening 100 foraccommodating the valve 74. An inlet passage 102, also cylindrical inshape, communicates with the interior of the heat exchanger, andcommunicates with the labyrinthine, or circuitous passage means 104which terminate in a passage 106 having a top wall portion 108 whichtapers upwardly as it extends outwardly, the passage 106 terminating inan outlet opening 110. The upper portion 46 of the heat exchanger isgenerally of a flat, platelike configuration, with the exception of theprojection or ribs 44 (FIG. 4) which extend upwardly, and the locatingbosses 112 for receiving the heat element means 52.

Referring now particularly to FIG. 2 and 4, it is shown that inassembled position of use, the upper and lower portions 46,48 of theheat exchanger are held in close proximity and in effect, form onerelatively massive unit.

Referring again to FIG. 4, fastener means in the form of rivets 50 areshown to be adapted to be received in openings 114 in the upper portion46 of the heat exchanger 40, by expanding the top portions thereof, in aconventional staking operation.

A preferred form of the heat exchanger 40 provides stiffening means inthe form of gussets 116 which support the projections 44 and aid in heattransfer downwardly therefrom to the plates 46,48 of the heat exchanger40.

Referring again to FIG. 2, it may be seen that the bosses 112 serve toassist in locating the heating element 52, by engaging the outerportions of the cover 54 thereof. One lead 1 18 of the cord 88 is shownto be engaged with a terminal 56 to supply current to the inside of thecover 54 which includes heating element means, 52 in the form of arheostat unit to be described in further detail herein. Since it isdesired that the heating element52 beplaced in intimate heat exchangerelation with the exchanger, so that heat generated therein will betransferred to the heat exchanger over a relatively large area thereof,it is preferred to dispose a layer of a filled, heat conducting greaseor other material is disposed between the bottom portion of the cover 54and the top portion of the upper portion 46 of the heat exchanger 40.

FIG. 2 also shows that the top cover 62 includes outer,

generally cylindrical walls 120, and inner, generally cylindrical walls122 which are received on a portion of the heat exchanger, and that thering 66 serves to receive, on an inner portion thereof, a projection 124extending downwardly from the dial unit 68. The projections 124 includesa slot or keyway 126 for engagement with the stem 58 of the heatexchanger. Although the opening 64 in the cover 62 is circular, dialstop means in the form of a flat surface 128 (FIG. 1) forming a chordacross the interior surface of the ring 66 limit rotation of the dial68. This feature serves to provide a limit to the degree of rotationaltravel allowed by the disc. Typically, the dial 68 may be rotatedthrough an arc of about 90 to 180, adjusting the resistance of therheostat in a manner to be described more fully herein. Proper alignmentof the dial, cover and shaft are provided, since the inner cylindricalwalls 122 of the cover 62 rest in a position on the top surface of theupper portion 46 of the heat exchanger which is determined by the legs130 of the inner walls 122.

Referring now to FIGS. 5 through 8, the construction of the heatexchanger is shown in greater detail. These FIGS. show that the outletmeans 42 is in the form of a short spout, and that a reentrant portion129 extends radially inwardly and is adapted to receive the legs 130(FIG. 1) which depend downwardly from the lower surface of the innercylindrical wall 122 of the cover 62. The dial 68 is relativelyrotatable, and the heat exchanger 52 has the cover portion 54 thereofheld fixed against rotation, so that moving the dial serves to rotatethe shaft 58 of the heat exchanger 40. The cover 62 supporting the dial68 is fixed against rotation by the legs 130, which are held in place bythe heads 132 formed thereon.

FIG. 5 shows the top surface of the plate 46, and recesses 132 for flushriveting the plates together. FIG. 6 shows the configuration of thepassageway 104 which extends between the inlet 102 (FIG. 7) and thepassage 106 communicating with the outlet 110. FIG. 6 also shows thatthe walls 134 forming the passageways 104 form additional heat transfermeans for equalizing the temperature throughout the heat exchanger 40.FIG. 8 shows the substantially flat top surface portion of the lowerportion 48 of the heat exchanger 40.

FIG. 7 illustrates the taper of the reentrant portion 94 of the heatexchanger which helps to center the nozzle 74 in the opening 100. Inreference to FIGS. 5 through 8, it can be appreciated that the heatexchanger unit 40, which is preferably made of two pieces of aluminum,is of a very simple construction, and is designed so that the partsthereof may be die-cast or otherwise simply formed, and may thereafterbe assembled together to form a unitary, relatively massive heatexchange unit with or without the use of adhesives, by a simple rivetingor staking operation. The resulting heat exchanger has excel- I lentthermal transfer characteristics to the foam moving through the passagesand provides excellent heat distribution from the element 52 throughoutthe body of the heat exchanger 40.

Referring again to FIG. 2, it is shown that a generally cylindricalhousing 138 forming a portion of the shell 22 and having a product inletopening 140 therein is provided to receive the product outlet 42 of theheat exchanger 40. A very minute opening 142 between the upper portionof the product outlet 42 and the housing 138 is shown, the importance ofwhich will be discussed later. Referring again to FIG. 2, the nozzleunit 34 is shown to include the inlet opening 140, a foamed productoutlet 144, and top and bottom wall portions 146,148, in addition to theside portions 32,34 referred to above. The top wall 148 of the nozzleslopes upwardly as it extends inwardly towards the body of the shell 22,while the lower walls 146 are generally horizontal.

Preferably, positioning the elements in place with the dispenser unit isaccomplished by the provision of an annular ring 150 extending outwardlyfrom the lower portion of the cover 62. This ring 150 is received in agroove 152 disposed in the shell 22. In an assembled relation, the legs130, including the heads 154 support the heat exchanger 40 in fixedrelation to the cover 62 which is in turn held fixed by the ring andgroove arrangement 150,152. The heating element means 52 may bemechanically locked or wedged in place between the two, or may beadhesively secured to the heat exchanger 40.

Referring now to FIGS. 9, 10 and 11, the electrical components of theinvention, including the heating element means 52 are shown. FIG. 9shows that a plug 155 or the like is adapted to receive 60 cyclealternating current from a household source, for example, and to feedthe current therefrom to the primary winding 156 of the transformer 90,and that the transformer 90 includes a core 158 and a secondary winding160, as well as leads making up a cord 88. Preferably, the transformer90 is a stepdown transformer having a ratio of secondary to primarywindings such that the output across the secondary is 24 voltalternating current. Preferably, the transformer is encapsulated into asingle unit and isolated from the remainder of the heating anddispensing unit 20.

A rheostat unit 162 includes a fixed terminal 56, to which one of theleads 118 is attached, and a high resistance wire 164 of substantiallength extends therefrom.

Movable terminal means 166 engages the resistance wire 164 at one pointalong the length thereof, and, as shown in FIG. 9, the resistance of thewire 164 in the secondary circuit at any one time is proportional to itseffective length. In the present invention, the terminal is movable onlybetween points B and C, and the resistance varies accordingly. Thus, ifthe full resistance available is represented by the length A to C, thenthe resistance at any time is equal to that resistance multiplied by theratio of length A to B divided by length A to C. The significance of theadjustment means for the rheostat will be discussed in greater detailherein.

Referring now to FIG. 10, the heating element means 52 is shown toinclude the outer shell section 54, which is preferably made of metal,and to include a top cover 168 and a rotatable inner stem 170, to whichis attached a contact arm 172 having a contact point 174 thereon. Theresistance wire 164 is in the form of a coil and comprises a largeplurality of turns of a fine, high resistance wire, disposed around anelectrically insulating support core 176. Contact means in the form of aslipring 178 engaging the stem completes the circuit between the upperterminal 56, the contact point 174 and the other end of the wire 164.The control stem 58 and the inner stem 170 associated therewith turninside an outer collar 180, which is held in place by locking means 182and is thus fixed against rotation.

A mass of filled, heat transferring grease or the like 184 is disposedwithin the heating element means 52, completely filling the inside ofthe outer cover 54, and surrounding the interior elements thereof. Thismaterial, which may be a silicone grease having a substantial proportionof finely ground zinc oxide therein, serves to dissipate the heat fromthe resistance wire 164 and direct it to the top portion 46 of the heatexchanger 40. The interface 186 between the top surface of the heatexchanger plate 46 and the bottom surface of the cover 54 may likewisebe coated or filled with such material.

Referring now to FIG. 11, it is shown that the contact arm 172 ispreferably designed to move through an arc of about 90 and 100, and thatthe resistance through which the current is passing in various positionsof adjustment varies between the resistance of the entire length of wire164, when the arm 172 is in the position shown in solid lines, to abouttwo-thirds to three-fourths of such resistance when the contact arm isin the position shown in the phantom lines. Thus,

the dial 68 and the dial stop means 128 (FIG. I) serve to permitmovement, but limit it to an are less than full rotation.

Accordingly, rotation of the dial 68 and the contact arm 172 operativelyassociated therewith serves to vary the amount of heat generated in theheating element means 52, and consequently, the amount of heattransferred to the heat exchanger 40.

When the resistance of the wire 164 in the length A-B is such that itmatches the impedance of the secondary of the transformer, according towell-known electrical principles, the maximum amount of energy will betransferred to the rheostat, and accordingly, the maximum amount of heatwill be generated. That is, when the external resistance or load of thecord 88 and the portion of the wire 164 between the terminals in equalto the impedance of the transformer secondary, maximum power istransferred. Since the relative re-' sistance of the cord is very smallsubstantially all of the power loss, and accordingly, heat generation,occurs in the rheostat. Moving the contact arm 174 clockwise as shown inFIG. 11 further increases the resistance to the point where greatlyreduced current flows through the heating element means 52 at thevoltage of the transformer, and accordingly only a small amount of poweris consumed and a small amount of heat is transferred to the heatexchanger. If the design is such that the heat exchanger is desired tobe left on" continuously a certain minimumamount of heat is suppliedthereto, maintaining an equilibrium at a temperature between 140 and 180F for example, as may be desired.

Accordingly, the. resistance of the wire 164 used to make up therheostat and the length thereof are calculated according to knownprinciples, keeping in mind the impedance of the transformer, and theunit is wired so that a resistance along a part of the wire l64 may bemade to approximate or equal that of the transformer secondary, andfurther wire is provided to increase the resistance of the heating coilto substantially diminish current flow through the heating coil.

In the embodiment just described, particular advantage is taken of theaction of the heat conductive, electrically insulating grease. Since thegrease performs the function of greatly aiding heat transfer from therheostat to the heat exchanger, sufficient current'may be passed throughthe rheostat to cause useful heating of the resistance coil thereof,without causing the rheostat to burn .out. Heat transfer is also aidedby the provision of the projections 44, the gussets 116, and the closephysical association between the cover 54 and the upper portion 48 ofthe heat exchanger 40. The filled grease 184 is extremely viscous, andwill not leak from the heating element means 52, even at extremetemperatures. Thus, in the operation of the unit, the transformer unit90 is plugged into a source, and energy flowing from the secondary 160thereof energizes the heat element means 52 to the extent determined bythe position of the contact arm, 172, which in turn is controlled bythedial unit 68. Heat generated therein is transferred through theelectrically insulated, heat conducting grease material to the heatexchanger where it serves to heat the relatively massive heat exchangerto a temperature of about 140 to 180 F. Thereupon, a downward pressureexerted on the top of the dial 68 or elsewhere on the exterior shell 22moves the entire assembly 20 downwardly relative to the base 72, inwhich the container 70 is locked, and thus, the valve 74 is moveddownwardly within the fixed container for dispensing the producttherefrom.

Thereupon, the foamable product contained in the container 70 movesthrough the opening 100, into the inlet passage 102, around thecircuitous passage 104, and out the opening 110 at the end of thepassage 106. The expanded, heated foamed cosmetic or like product thenmoves out the nozzle formed by the two portions32,34 for reception bythe user. When the downward pressure on the shell 22 is released, theresiliency afi'orded by the aerosol valve lifts the entire containershell 22 and the heating means associated therewith upwardly, cuttingoff the flow of product from the container 70.

One important feature of the present invention is that the very minutespace or opening 142 disposed above the cylindrical housing 138 allowsescape therethrough of any gaseous product which separates from thefoamor emulsion which has completely filled the nozzle formed by theportions 32,34. In prior art designs, the continued heating of theproduct trapped in the high temperature region of the heat exchangercaused continued expansion thereof, pushing the product held in thenozzle outwardly in an undesirable drooling effect. This effect isminimized or precluded in the present design, since escape of gasupwardly through the opening 142 causes a slight vacuum effect whichtends to prevent forward movement of the foam in the nozzle. Theupwardly angled disposition of the top wall portion 108 of the passage106 also contributes to this effect, since evolving gas tends to moveupwardly along the slanted top wall 108, whereas the foam tendsexemplary, with a heat exchanger of the construction illustrated, withthe dial 68 at a high temperature setting, sufficient heated foam may bedispensed, for example, to provide in rapid succession, lather for fouror five shaves or more without excessive loss of heat from theheat'exchanger unit 40. On the other hand, when the dial 68 is moved sothat the rheostat is set at a low heat position, the heat exchanger unitwill maintain a desired temperature of between and F. without undueconsumption of current. Because of the use of the stepdown transformer90, which is isolated from the remainder of the unit, the danger ofelectrical short circuit hazards and the like are diminished, sincerelatively low voltage, high current operation is employed.

The provision of the relatively small passages 104 enhances the abilityof heat exchanger 40 to transfer heat to the foam before the expansionof the foam is complete. Therefore, the inherent resistance of the foamto temperature rise caused by its own insulating properties isminimized, partially because the foam is largely in the liquid ratherthan in the emulsion form. Subsequent expansion of the foam, whilecausing a temperature drop, does not excessively lower the temperaturethereof.

Referring now to FIG. 15, an aerosol container 188 having a foamableproduct therein, and especially adapted for use with the presentinvention, is shown. The features of this container 188 and the producttherein, and the reasons why such con tainer and product are preferredwill now be discussed.

The container 188 is a conventional metal aerosol can, and includes anexterior body portion 190, an upper end or dome portion 192 and a lower,preferably concave bottom end portion 194, the ends 192,194 beingaffixed to the body 190 by conventional double seams 196,198, in amanner well known in the art. An aerosol mounting cup 200 surmounts thedome, and is held in place therein by a crimped, outwardly extendingbead 202 which is also conventional in the art. An aerosol dispensingvalve 204, of any well-known type, is aflixed within the mounting cup200, for dispensing the product. Disposed inside the body 190 is aninterior container 206, the exterior walls 208 of which include aplurality of pleats or bellows. The upper portion of the inner container206 is affixed to the mounting cup 200 in a liquid and gastightrelation, as at the seam 210. A bottom wall portion 212 joins the walls208 to complete formation of the inner container 206.

In accordance with the present invention, the inner container 206contains a foamable product 214 having, for example, water, soap, andone or more additional emulsifying agents therein, as well as a gasemulsified or dissolved therein for purposes of expanding the product214 when it is exposed to the atmosphere. For example, a hydrocarbonmaterial such n-butane gas may be used, since this gas is readilymaintained in the liquid state with a low overpressure orcounterpressure, say to p.s.i., within a temperature range in which theinvention would normally be used. Thus, the composition 214, within thecontainer is in a liquid state, but contains a volatile gas which isexpanded, upon release to atmospheric pressure, without the need forapplication of additional heat. A liquid phase of the butane or likelow-boiling gas will remain present as long as sufficientcounterpressure is maintained thereon, and the flexible sidewalls 208insure that such pressure will be transmitted to the interior of thecontainer 206.

Inside the outer body 190, and outside the inner container 206 is apropellant 216 which is partially in the liquid form, and which alsoincludes a vapor phase 218-in equilibrium with the liquid. Afluorocarbon gas or mixture thereof having a 72 F. vapor pressure ofabout to 50 p.s.i. is typically used for this purpose. At an operatingpressure of 40 pounds to a square inch, for example, and a temperatureof 72 F., both liquid and vaporare present, and as long as acounterpressure or overpressure of 40 p.s.i. is maintained, more andmore liquid fluorocarbon will volatilize as vapor is removed from thecontainer, or as additional headspace is provided for expansion thereofwithout increasing the pressure, that is, by reduction in size of theinner container 206.

With a container having a volatilizable liquid propellent 216 heldoutside the inner container 206 and a shaving product, for example, keptwithin the inner container 206, upon dispensing the contents, foamableproduct 214, not having a portion of the contents thereof volatilizeduntil after dispensing from the container 206, retains the same.relative proportion of vapori'zable and liquid material until all ofthe product 214 is dispensed.

Inasmuch as the relative proportion of ingredients within the innercontainer 206 remains the same during successive dispensing operations,the heat capacity thereof also remains the same, and the foam isdispensed at a uniform temperature, regardless of the amount of productremaining in the inner container 206. In prior art containers andcompositions, since the more volatile components were exhausted from thesolutions or emulsions before the less volatile components, the latheror other composition would vary in temperature as its composition andheat capacity varied during dispensing. Ac cordingly, the combination ofthe flexible inner container with the use of propellants and foamingagents having the liquidvapor phases and pressure relationships setforth herein is particularly advantageous for use with the combinationheating unit, and dispenser of the present invention.

Referring now to FIGS. 12, 13 and 14, modified forms of some of theelements of the combination heating and dispensing unit 20a of theinvention are shown. Referring particularly to FIG. 12, the dial 68a isshown surmounting the cover 62a, which includes the opening 64a throughthe ring 66a having the chord member or dial stop 128a associatedtherewith. The cover element 62a also includes the supporting ring 150a.A transformer unit 90a is similar to its counterpart in the earlierdescribed embodiment. In this embodiment,

however, the heating element means 52a is combined into a single unitwith the heat exchanger 40a, and the resistance wire 164a is embedded inthe top plate 46a of the unit. Terminals 56a are connected to the cord88a, and a contact arm 172a terminating in a contact point 174a isdisposed on the lower portion of the stern a for establishing electricalcontact with the coil of wire 164a and the terminal 56a associatedtherewith. The wire 164a is wound around an electrically insulated core176a, and insulating grease 184a is disposed in the recess 222 withinthe upper portion plate 46a of the heat exchanger 402. The radiallyinner end of the contact am 224 which is attached to the terminal 56aincludes a slip ring 226 surrounding the lower portion 170a of thecontrol stem 58a. The bottom portion of the heat exchanger 48a, thepassages therein, and the other elements thereof are similar to theircounterparts shown in FIG. 1 through 8. In all operations respects, theunit shown in FIGS. 12-l4 is the same as that shown in FIGS. 1 through6. The differences residing in the construction of the heat exchanger,and other variations of the basic concept of the invention, are.structural only.

The heat exchanger means 52, shown, for example, in FIGS.

18 and 10l1 represents a modification of a commercially availablerheostat modified so as to render it suitable for use as a heatingelement, whereas'the form of the heat exchanger and heating elementmeans shown in FIGS. 12 through 14 represents a modification made to anexisting heat exchanger to accommodate the desired rheostatconstruction. This form provides increased efficiency and economy, byreason of surrounding the resistance wire 164a on three sides with theupper portion 46a of the heat exchanger 52a.

One particularly advantageous aspect of the invention is the use of thefilled insulating grease in combination with a rheostat unit to providea heating element having excellent heat transfer characteristics. Such agrease, which is preferably a silicone grease having substantialportions of an inert filler therein, such as zinc oxide, to-increase theheat transfer rate thereof, is commercially available, General ElectricInsul Grease 641" and Dow Corning Heat Sink Compound 340" being typicalbrands thereof. The use of the thermally conductive, electricallyinsulating grease makes it possible to utilize a relatively lighter lessexpensive rheostat than could normally be used, or to use a lighter dutyrheostat in place of a more expensive heating coil. In this aspect, theheating element is useful in environments other than with the dispenserunit of the present invention; it is useful in several otherapplications, including other forms of electrically heated appliances.For example, a typical rheostat normally rated at 4 watts, when exposedto ambient air at 70 F and having 4 watts of energy passed therethrough,will rapidly heat to 420 F. or more, and, if maintained at suchtemperature, will rapidly burn out. However, if the rheostat is packedwith a filled, heat conductive, electrically insulating grease, therheostat will not rise above a temperature of 320 F., even where theambient temperature rises to as much as 200 F. Thus, placing therheostat in intimate heat exchange relation with an element to beheated, and surrounding the resistance coils thereof with a thermallyconductive, electrically insulating compound, enables sufficient heat tobe transferred away from the rheostat so that the rheostat will notoverheat. On the other hand, if no heat-conductive grease is used, aresistance heating element, particularly a rheostat, would have to bemuch heavier for the same heat output. Thus, one aspect of the presentinvention is the provision of an improved heating unit for appliancesand the like, particularly a variable current, variable temperatureheating unit of very low cost.

It will thus be seen that the present invention provides a novel heatingelement means, a novel heating element and heat exchanger assembly foruse in a dispenser, a novel combination foamable product, propellant andcontainer, and a novel combination heating and dispensing unit for anaerosol product, having numerous advantages and characteristics,including those hereinbefore pointed out, and others which are inherentin the invention.

lclaim:

.1 I. A dispenser unit for heating and dispensing an aerosol productfrom a pressurized container, said dispenser comprising, in combination,an exterior shell member having an opening at one end thereof forreceiving an aerosol container, and a product heater and dispenser inthe other end of said shell, said heater and dispenser comprising a heatexchanger having and inlet for receiving a product dispensed from anaerosol container, an outlet for such product, and circuitous passagemeans connecting said .inlet to said outlet, said outlet in said heatexchanger being generally horizontally directed and including a passagehaving a top wall portion which tapers upwardly as it extends outwardly,said passage terminating in an outlet opening, said exterior shellmember, including an exterior, product dispensing nozzle associatedtherewith, said nozzle including a dispensing opening and being incommunication with said outlet opening at a substantially foamtightconnection, said nozzle having a substantially larger cross-sectionalarea than said outlet opening and vent means for allowing gaseousproduct-foaming components to escape upwardly within the foamtightconnection between said heat exchanger outlet opening and said nozzledispensing opening.

2. A dispenser unit for heating and dispensing an aerosol product from apressurized container, said dispenser comprising, in combination, anexterior shell member having an opening at one end thereof for receivingan aerosol container, and a product heater and dispenser in the otherend of said shell, said heater and dispenser comprising a heat exchangerhaving an inlet for receiving a product dispensed from an aerosolcontainer, an outlet for such product, circuitous passage meansconnecting said inlet to said outlet, and variable resistance heatingelement means for heating said heat exchanger, said heating elementmeans being in the form of a manually adjustable rheostat having aresistance element therein and means lying externally thereof forselectively adjusting the resistance value thereof, said rheostat havingan exterior metal cover and being disposed atop said heat exchanger,said heat exchanger including generally vertically extending portionscontacting said metal cover, the manually adjustable rheostat having theinterior portion thereof filled with an electrically insulating,thermally conductive heat transfer material to facilitate heat transferbetween said resistance element of said rheostat and said heatexchanger.

3. A dispenser unit for heating and dispensing an aerosol product from apressurized container, said dispenser comprising, in combination, anexterior shell member having an opening at one end thereof for receivingan aerosol container, a product heater and dispenser in the other end ofsaid shell, a stepdown transformer having a primary winding adapted tobe operatively associated with a power source and a secondary windingfor supplying current to said heater and dispenser unit, said heater anddispenser unit including a heat exchanger having a circuitous productpassage therethrough for receiving product from said container anddispensing it from said heat exchanger in a heated condition, said unitfurther including a manually adjustable variable resistance heatingelement having the terminals thereof attached to said secondary winding,said resistance element being surrounded by and in intimate heatexchange relation with an electrically insulating, heat conductivematerial, said material being also in intimate heat exchange relationwith a portion of said heat exchanger, said resistance element beingadjustable at least between a first resistance value calculated toproduce maximum power transfer in said transformer and anotherresistance value much higher than said first resistance value andadapted to produce a greatly reduced power transfer in said transformer.

4. A dispenser unit as defined in claim 3 in which said heat exchangercomprises a substantially solid mass of metal, with the thickness of theportions beneath said circuitous passage means and the thickness of theportions above said circuitous passage means being substantially greaterthan the height of said passage means.

5. A dispenser unit as defined in claim 3 in which said variableresistance heating element means is disposed within a groove in saidheat exchanger, and in which said groove is led with said heat transfermatenal for providing electrical insulation between said heating elementmeans and said heat exchanger, and for increasing heat transfer betweensaid heating element means and said heat exchanger.

6. A dispenser as defined in claim 3 in which said means for insulatingsaid heating element means and for promoting said heat transfercomprises a silicone grease material including a filler associatedtherewith, said filler including a metallic oxide-containing compoundhaving a higher heat transfer capacity than said silicone greasematerial.

